In SHM, displacement is given by:
\[
x = A \cos(\omega t)
\]
Given, \( x = \frac{A}{2} \Rightarrow \frac{A}{2} = A \cos(\omega t) \Rightarrow \cos(\omega t) = \frac{1}{2} \Rightarrow \omega t = \frac{\pi}{3}
\]
Now,
\[
\omega = \frac{2\pi}{T} \Rightarrow t = \frac{\pi}{3} \cdot \frac{T}{2\pi} = \frac{T}{6} = \frac{2T}{12}
\]